doi:10.1016/j.elspec.2006.11.060
Copyright © 2007 Elsevier B.V. All rights reserved.
Probing the band structure of LaTe2 using angle resolved photoemission spectroscopy
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D.R. Garciaa, b, 
, 
, S.Y. Zhoua, b, G.-H. Gweona, 1, M.H. Jungc, Y.S. Kwond and A. Lanzaraa, b
aDepartment of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
bMaterials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
cNational Research Laboratory for Material Science, KBSI, 52 Yeoeun-Dong Yusung-Gu, Daejeon 305-333, South Korea
dDepartment of Physics, Sung Kyun Kwan University, Suwon 440-746, South Korea
Available online 8 December 2006.
Abstract
With the current interest in the rare-earth tellurides as ‘high temperature’ charge density wave materials, a greater understanding of the physics of these systems is needed, particularly in the case of the ditellurides. We report a detailed study of the band structure of LaTe2 in the charge density wave state using high-resolution angle resolved photoemission spectroscopy (ARPES). From this work we hope to provide insights into the successes and weaknesses of past theoretical study as well as helping to clear up prior ambiguities by providing a firm experimental basis for future work in the tellurides.
Keywords: Photoemission; Tellurides; Charge density wave; Band structure
Fig. 1. (a) ARPES constant energy intensity map averaged in energy from EF to 80 meV binding energy and symmetrized over x=0. Beam energy was 55 eV with a polarization reflected in the inset. Orange dashed lines indicate the Brillouin zone boundaries. By comparison with the non-CDW LDA FS calculation [16], indicated as white dashed lines, we find moderate agreement. However, as we approach a photon energy of 110 eV, more features are revealed. (b) ARPES constant energy map, unsymmetrized, averaged from EF to 100 meV binding energy using 110 eV photons. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.)
Fig. 2. (a) Momentum distribution curves (MDCs) taken (1) along the M–Γ –M direction and (2) parallel to M–Γ –M but slightly shifted. From these we can discern the twin peaks of the inner diamond while the spectral of the bands near the M point is strangely suppressed but only along the high symmetry direction. (b) MDCs along Γ –M at increasing binding energies showing the dispersion of the inner diamond band up into the energy range of Fig. 1. Red MDCs indicate where the curve becomes dispersionless. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.)
Fig. 3. (a) ARPES constant energy image plot centered at 130 meV and integrated over 60 meV. Orange arrows indicate bands near the X points which break mirror symmetry. (b) A similar plot centered at 270 meV and integrated over 80 meV showing how the non-mirror symmetric bands disperse by splitting in two. (c) LEED done on LaTe2 indicating both main peaks (MP) but also a superstructure (SS) which breaks mirror symmetry. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of the article.)
Fig. 4. (a)–(d) Constant energy cuts integrated over 60 meV, with first derivative used to enhance band edges, centered at binding energies 450, 560, 700 and 820 meV, respectively.
Fig. 5. (a) ARPES image plot showing dispersions along X–Γ –X down to nearly 4 eV in binding energy. (b) ARPES image plot showing dispersions along X–Γ –X down to nearly 1.5 eV in binding energy. Overlaid on both plots is the predicted LDA band structure which, in some cases, is renormalized based on the data. (c) LDA band structure calculation along X–Γ –X. Bands that have been renormalized are indicated by arrows showing the proposed shift in energy from their original locations (gray dashed lines). (d) Energy distribution curves (EDC’s) down to 3 eV in binding energy taken along Γ –X direction.
Fig. 6. (a) ARPES image plot showing dispersions along M–Γ –M down to nearly 4 eV in binding energy. (b) ARPES image plot showing dispersions along M–Γ –M down to nearly 1.5 eV in binding energy. Overlaid on both plots is the predicted LDA band structure which, in some cases, is renormalized based on the data. (c) LDA band structure calculation along M–Γ –M. Bands that have been renormalized are indicated by arrows showing their proposed shift in energy from their original locations (gray dashed lines). (d) Energy distribution curves (EDC’s) down to 3 eV in binding energy taken along Γ –M direction.
Fig. 7. (a) ARPES image plot showing dispersions along M–X–M down to nearly 4 eV in binding energy. (b) ARPES image plot showing dispersions along M–X–M down to nearly 1.5 eV in binding energy. Overlaid on both plots is the predicted LDA band structure which, in some cases, is renormalized based on the data. (c) LDA band structure calculation along M–X–M. Bands that have been renormalized are indicated by arrows showing their proposed shift in energy from their original locations (gray dashed lines). (d) Energy distribution curves (EDC’s) down to 3 eV in binding energy taken along X–M direction.
Corresponding author at: Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA. Tel.: +1 847 373 3247.
1 Present address: Physics Department, UCSC, Santa Cruz, CA 95064, United States.
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0.75 above which the in-plane ferromagnetism takes place. We also find that the six small hole pockets near the 
